The present invention relates to a connector by which helically grooved electrical conduit can be rigidly secured in a housing such as a junction box, fixture or the like.
The problem of securely fastening flexible electrical conduit in a junction box has been solved in several ways in the past. One such solution involves die cast sleeves which are threaded into the opening in the junction box and then secured by a locking nut. Conduit is then fed through the sleeves and clamped by screw-tightening a bar assembly to bear upon the inserted conduit. While this method serves the ultimate purpose of holding the electrical conduit in the junction box, it has several drawbacks.
Connectors involving die cast sleeve assemblies typically have several separate subparts which are manufactured and then loosely assembled and sold as a connector unit. Individual assembled units must then be dissembled for installation at the worksite. Such a complicated manufacturing and installation technique is very expensive and time-consuming. Also, junction boxes of the type in which the connectors of the present invention are designed for use are often located in out-of-the-way places to which access is limited. Die cast sleeve assemblies have proven difficult to use where needed because the numerous small parts require ample space and a dexterous hand to assemble and fix in position in the junction box. Finally, die cast assemblies by their very nature tend to be somewhat weighty and costly.
In U.S. Pat. No. 4,012,578, a connector clip is described which has a xe2x80x9cbody portion generally defined by flat wallsxe2x80x9d. The body portion rather than being cylindrical as in the patent discussed above has a triangular, square, pentagonal, or hexagonal cross-section, the flat walls assertedly better engaging the conduit outer surface. In practice, however, the patented device fails to engage the conduit evenly and the conductor is only loosely connected to the junction box, remaining subject to unwanted disengagement.
Incorporated herein by reference is the disclosure of U.S. Pat. No. 4,880,387, which is assigned to the same assignee as is the present invention and application. There is disclosed a one-piece connector which solves many of the foregoing problems, particularly when used for smaller conduit. The patented connector achieved its good results largely through the use of multiple gripping barbs formed on flexible arms which engage the conduit over relatively broad areas. Also, relatively long retaining members cooperate with flanges to lock the connector into the opening of a junction box or other housing.
A need has arisen for even better performance, especially with the majority of conduit being installed in openings of xe2x85x9exe2x80x3 (standard knock-out hole), and the primary object of this invention is to fill that need.
In the present invention, a more rugged barb design for engaging the conduit provides increased resistance to the conduit being pulled out of the connector. Also, by the use of multiple flexible arms, the resistance of the connector to pullout from the junction box opening has been increased. The multiple flexible arms also contribute to the radial stability against side forces on the conduit when it is engaged in the junction box opening. Lastly, an additional flexible arm engages the outside diameter of the conduit, increasing the resistance against unscrewing.
For a better understanding of the present invention, together with other and further objects, features and advantages, reference should be made to the following description of a preferred embodiment which should be read with reference to the appended drawing in which: